This is a proposal to carry out secondary analyses of the National Longitudinal Study of Adolescent health (Add health) data set to examine the protective effects of sports involvement on adolescents' likelihood of engaging in high risk sexual behaviors. Risky sexual behaviors, in the context of this study, refer to self-reports of early, frequent, and unprotected sexual encounters which can result in unplanned pregnancies, childbearing, and increased chances of contracting sexually transmitted diseases (STDs). The impetus for the study comes from recent finding that participation in sports is associated with lower risky sexual behaviors among adolescent girls but not boys. The significance of the problem addressed by the proposal rests not only in a socially desirable public health outcome (reduction of risky sexual behaviors) but also in the widespread availability of the probable solution (participation in sports). In other words, if we can elucidate the mechanisms whereby sports participation is associated with lower levels of risky sexual activity among different groups of adolescents, we will have provided the scientific basis for prevention efforts on a socially important issue for which the federal state, and local governments and social service agencies have already invested considerable resources. The specific aim of research is to test competing and complementary hypotheses formulated to explain how and for whom sports involvement has a protective effect on self-reported risky sexual behaviors. These hypotheses will be tested primarily in a structural equations modeling framework. This approach allows us to explicitly model measurement error and remove its effects from the relationships of interest. In addition, several systems of equations can be modeled simultaneously, allowing tests of pathways of influence and compare these pathways across multiple groups of individuals. In connection with explaining " how " sports participation can be conducive to low risky sexual behaviors, we will postulate mediating processes through which sports involvement influences sexual behavior. The end result of the proposed scope of work will be models that integrate the competing and complementary hypotheses to explain the observed relationship among sports participation and lower risky sexual behaviors. The models will incorporate individual differences, interpersonal and contextual processes that protect adolescents from the negative development outcomes associated with high-risk sexual activity.